This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Recent work from our group and others has demonstrated that the benefits of adult stem cell administration are conferred primarily through the paracrine effects of secreted factors. Low numbers of long-term engrafting cells indicate that direct cell replacement is only a small part of what stem/progenitor cells do to heal tissues after injury. Following migration into areas of injury, adult stem cells release numerous growth factors and cytokines that mediate tissue repair by reducing apoptosis and necrosis of surrounding cells, increasing angiogenesis and perfusion, influencing inflammatory responses, and increasing the reparative activities of endogenous tissue stem cells. We have determined that there are subpopulations of human bone marrow-derived progenitor cells with different repertoires of secreted factors. Therefore, it is of interest to determine whether particular subpopulations of bone marrow progenitor cells are best to treat certain injuries based on the proteins and peptides that they release.